Whilst other scholars had previously thought of Mark’s Gospel as the foundation for Luke, B.H. Streeter refutes these views and suggests the opposite. He named this theory ‘Proto-Luke’, which suggests that while putting together his gospel, Luke wrote an early draft which was primarily made up of Q and L sources, before he became acquainted with Mark. This Marcan material was used as a secondary source, which was later slotted into an existing composition, which makes up the present gospel.
The previous draft, which excluded any Marcan content, was dubbed Proto-Luke. Arguments supporting Streeter’s hypothesis include the very structure of Luke’s Gospel. Rather than interweaving the Q, L and Marcon sources together, the gospel alternates between five large blocks from Mark and the smoothly flowing Q and L sections. “Mark is a quarry from which stone is obtained to enlarge an existing building.” – Taylor.
How Q and L are combined together suggests they were used in harmony with each another, which agrees with the Proto-Luke theory.
It seems that Luke used Q to carefully select sayings of Jesus which would expand his own research. However, material sourced from Mark is dropped in without mixing with Q and L information. The scholar Taylor argues that when we exclude the Marcan content, the Q and L material flows in a understandable way, a so-called ‘relative continuality’. Therefore, the suggestion that a Proto-Luke version of the gospel existed prior to the introduction of Mark is a perfectly acceptable argument. Stanton applied this to the passion narrative by removing the Marcan verses and found that from Luke 22:14 and 23:53, (163 verses), only twenty were totally dependant on Mark. “If they are removed we still seem to have a coherent non-Marcan passion narrative.” – Stanton. The beginning and ending of Luke’s Gospel contain no material drawn from Mark.
If Luke already had a gospel before he came across the Marcan material, then it makes sense that he would leave his own introduction and conclusions untouched whilst editing the middle in order to insert blocks from Mark. However, Stanton notes that Proto-Luke may have begun at 3:1, due to the formal introduction: “In the fifteenth year of the reign of Tiberius Caesar…” The fact that Luke omits so much of Mark, which accounts for a third of Luke, may suggest that he is giving priority to his original Proto-Luke limitations. Stanton talks of Luke’s disloyalty to his Marcan source: “At many points, [only two of which can be mentioned here,] Luke’s gospel seems to betray its Marcan basis”. If Mark was Luke’s framework for his gospel, how can we explain the omission of this much Marcan material? Another point to consider is the restrictions of writing on a papyrus scroll, the length of this would limit the degree to which Luke could supplement Proto-Luke with Marcan information.
On the other hand, many arguments discredit the Proto-Luke hypothesis. As of yet, scholars cannot agree on the verses that came from Mark and the verses which belong to Q and L, but the scholar Tuckett has claimed to have identified phrases from Mark in amongst blocks of Q and L. If he is correct in these claims then the Proto-Luke theory is doubtful. Having said that it may have been possible for Q and L to have existed in a coherent order without any Marcan material, there are still holes in the narrative flow that Q and L create. This point can lend itself to arguments against Proto-Luke, leading some scholars to call it “an amorphous collection”. If it doesn’t read like a single document, then perhaps Proto-Luke never existed. For example, between 8:3 and 9:51, when Marcan material is removed, an awkward gap is revealed, as there is nothing about Jesus’ time in Galilee. Discontinuity like this in Proto-Luke goes against the hypothesis that it ever existed.
Another view twists one particular argument in favour of Proto-Luke; about how Q and L are combined, with Marcan content awkwardly slotted in. We are familiar with Luke’s compositional style, it is also seen in Acts, which features abrupt shifts between the “we” sections and the rest of the gospel. There are also suggestions that the infancy narrative may have been added to Luke later, as it doesn’t seem to fit with the rest of the Gospel. These features of Luke’s writing indicate his tendency to throw his various sources of information together. Then this style may not have been unique to the Marcan material that Luke supposedly added to his Proto-Luke draft. Maybe this is just how Luke prefers to set out all of his writing? Hence, the proto-Luke theory looses credibility if this is simply the manner in which Luke constructs all his documents.
Luke may have felt that Mark’s Gospel was too important to alter in any way, so he slotted it into his Gospel in the same manner he did with other important sources. Scholars such as Fitzmyer propose that certain doublets in the Marcan material can show that Mark was actually a primary source. There are a number of repeated, similar phrases, for example “to all those who have more will be given, but for those who have nothing even what they have will be taken away” features in 8:18 and 19:26. When this happens, one version of the phrase comes from Mark and the other originates from ‘Q’ (shared with Matthew).
When we tally up where all of these phrases come from, most are sourced from Mark, leading the theory that Mark was actually an early framework for Luke’s Gospel. Whilst piecing his gospel together, Luke may simply have decided to use Mark in block form; however that does not mean that Marcan material was added in later, in a two-stage composition (as noted by Taylor). Guthrie commented on this hypothesis, and said that although it had grounding, it was too weak to justify a full inquiry: “although the hypothesis may have explained certain features in the disruption of Luke, it cannot be said that features demand the hypothesis”.